The invention relates to the transfer of a thread from a full package to an empty tube of a thread winding machine.
In the case of the winding of threads on winding machines having a revolver carrying the winding mandrels, the thread (which is still feeding at the termination of the winding operation) must be transferred from the full package onto the empty tube. This is brought about by a series of steps, including the turning of the revolver to shift the empty tube to the winding position. The transfer should occur without waste of thread, and an end ridge of thread should be formed on the full package, and a thread ridge should be formed on the new tube or its mandrel outside of the normal winding stroke.
Methods and devices for the execution of such a package change are known. A first type of such device moves the tube, or the winding mandrel, axially during the package change so that the ridge is produced at the desired position. These devices have the disadvantage that the winding mandrels, rotating on the revolver at high rotational speed, must be made axially movable, which involves a high cost for a mechanism supporting the winding mandrels on the revolver.
From U.S. Pat. No. 4,216,920, a winding device is known in which the thread being wound on a package is removed from a reciprocating guide by a first element in the form of a shifting guide and is deflected into a plane in which the catcher slot of the empty tube lies. A rodlike second element is fastened on the revolver carrying the winding mandrels and is situated downstream of the first element with reference to the direction of thread travel. This second element deflects the thread traveling to the full package. A third element in the form of a groove or a pawl or a change-over guide deflects the thread axially with respect to the point of contact of the thread and the second element in such a way that the thread comes to rest in the afore-mentioned plane of the catcher slot of the empty tube.
This known device has the disadvantage that the second element, which is connected permanently to the revolver and consequently can be rotated in synchronism with the winding mandrel, still has a deflected thread running at more than 90.degree. in a first plane perpendicular to the winding mandrels (see FIG. 4 of U.S. Pat. No. 4,216,920) and, after the intervention of the third thread guide, additionally deflects the thread by a further angle of more than 45.degree. (see FIG. 5 of U.S. Pat. No. 4,216,920). Such severe deflections, in conjunction with the high speed of the threads, might lead to thread damage or even to thread breaks. Furthermore, the deflection of the thread through the second element lasts for a relatively long period, starting shortly after the swiveling away of the full package from the friction roller up to the point of time of the thread transfer onto the empty tube, so that a considerable amount of thread might be affected.
An object of the present invention is to develop methods and apparatus for the transfer of the thread from a full tube to an empty tube, whereby the thread being wound on the full package during the transfer stage is only deflected for a very short time, and the deflection of the thread only undergoes a further deflection during the transfer into the catcher slot.